Guys I was randomly walking about and a dragon lands beside me, if I defeat it (which I am more than able) will this *bleep* up any quests, storylines etc? I really don't want to miss out on anything. I am level 34 on my second vocation, but have done virtually zero main story quests.

Nope. It's a wandering miniboss. If you're not done with the final battle quest then I'm guessing you're in Devilfire Grove just west of the rest camp near shadow fort. That is the only drake spawn before you open up everfall.

You can kill him, rest for 5 days and kill him some more with no story/quest consequence.